The present invention relates generally to monitoring operation and maintenance of a telecommunication network, such as ATM, Frame Relay or packet based networks. In particular, it is directed to tracing the route of a virtual connection between two nodes of a network, using trace cells, test cells or specially defined OAM (Operations, Administration, and Maintenance) fault management cells.
Telecommunication networks must be properly maintained to ensure that adequate network performance is achieved and that end-user services are supported. Maintenance functions include xe2x80x9cperformance managementxe2x80x9d (continuous in-service performance monitoring for proactive warning of performance degradation), xe2x80x9cfault managementxe2x80x9d (detection and location of network trouble and failure), and configuration management (provisioning). In performing these functions, especially configuration management, it is important to be able to trace the route of a virtual connection which exists between two nodes through a network. The route is made up of a series of links, each link being formed by a pair of nodes or connection points. To trace a route, it is therefore necessary to determine the identities of such nodes through which a virtual connection is routed. These identities also enable the network links and segments in the connection to be identified. Depending on the identity level of detail, the network elements such as cross connects and switches in each node can also be identified.
Specifically, the tracing of the route is required for the following reasons:
to generate a record of the connection route in terms of the identities of the nodes and network elements in the route;
to verify that the trace record matches the provisioning database record of the connection, and to update the database if desired, e.g., after a route reconfiguration; and
to fault locate a misroute, i.e., determine the network element, node and link where a misroute has occurred.
It is therefore an object of the invention to provide a method of identifying nodes in a network through which a connection is routed.
It is another object of the invention to provide a method of tracing nodes in a network by using a trace cell.
It is a further object of the invention to provide a method of managing a network by tracing nodes through which a connection is routed.
Briefly stated the invention is in the area of management of a network which is holding a virtual connection between two end nodes by a route consisting of one or more links. The invention is directed to a method of identifying a node forming one end of a link of the route. The method comprises a step of a monitoring node on the route sending a trace cell downstream towards one or both end nodes, the trace cell having a link count field set to a predetermined count and carrying the identification of the monitoring node. The method further includes steps of nodes downstream on the route successively decrementing the link count field and forwarding the trace cell downstream, and a loopback node downstream on the route receiving the trace cell and sending to the monitoring node a loopback trace cell carrying the identification of said loopback node, if the decremented link count field equals 0.
According to another aspect, the invention is directed to a method of identifying nodes forming the links of the route comprising a step of a monitoring node on the route sending a trace cell downstream towards one or both end nodes, the trace cell having a link count field set to a predetermined count and carrying the identification of the monitoring node. The method further includes steps of each of the successive nodes downstream on the route receiving the trace cell, decrementing the link count field, forwarding downstream the trace cell having the decremented link count field, and sending to the monitoring node a loopback trace cell carrying the identification of each said node. The method also includes a step of a loopback node downstream on the route sending to the monitoring node a loopback trace cell carrying the identification of said loopback node if the decremented link count field equals 0.
According to yet a further aspect, the invention is directed to a method of identifying nodes forming the links of the route comprising steps of a monitoring node on the route sending a plurality of trace cells downstream towards one or both end nodes, each trace cell having a link count field set to each of a plurality of predetermined counts and carrying the identification of the monitoring node. The method further includes steps of nodes downstream on the route decrementing the link count field and forwarding the trace cell downstream if the decremented link count field is larger than 0. The method finally has a step of each of the nodes downstream on the route receiving the trace cell and sending to the monitoring node a loopback trace cell carrying the identification of each said node if the decremented link count field equals 0.